The number of protons and neutrons in the nucleus of an atom must always be equal, in order for the strong nuclear force binding them together to be effective. True or false?

Question

jfraser · Answer

grab a periodic table and look at the average mass of carbon: ~12, so 6protons, 6 neutrons. Now look at the average mass of gold and tell me true or false.

anonymous · Answer

Alright, doing that now!

anonymous · Answer

Well I know that the mass of carbon-12 is smaller than the mass of gold. I don't think that the protons and  neutrons in gold are equal though, I could be wrong.

jfraser · Answer

it's not the mass of the 2 atoms that's important here. It's the number of protons and neutrons that they each have.

Carbon's average mass is ~12, so 6 protons and 6 neutrons.

Gold's average mass is ~197, but only has 79 protons. The remaining mass comes from 118 neutrons. 79 and 118 are definitely not equal.

jfraser · Answer

Most atoms with fewer than 20 protons also tend to have the same # of neutrons. As the atoms get more and more protons, the number of neutrons increases even faster, so the A/Z ratio (mass/protons) gets larger and larger in order for atoms to be stable.